Shido's Vendetta
by paomayo
Summary: When his sister mysteriously disappeared during the Settlement Defense Front's failed invasion on Earth, a mission that can find any leads of her went wrong and sent him to another dimension that is decades back in time. However, evidence of her and the people involved in her kidnapping were later revealed to him, bringing him a glimmer of hope to be reunited again.


_All trademarks, properties and copyrights associated with the manufacturers, models, trade names, entertainment and brands depicted in this fanfic are the property of their respective owners._

In a Japanese city, life moves on. Many of the civilians go to work, the children go to school, and the train bound for Tokyo arrived a minute ahead of schedule. To them, they are a normal routine depending on the position they are in.

"...uggghhhh...what happened?"

For one man, however, it is way different. For one, he was part of the Special Combat Air Recon, a special forces branch for the Solar Associated Treaty Organization. The second is that he was participating in a mission that went horribly wrong and ended up in a city that is decades back in time.

He began to get back on his legs while getting hold on his customized EBR-800 hybrid sniper rifle. Another check on the scenery made him wonder.

"Okay then... where am I exactly?" He asked himself before moving. "This doesn't look like my time period right now."

As he continued moving, he began to do a check on his equipment including his suit and boost rig for integrity via the Intelligent Visual Computer System. A thorough scan made him relieved as it showed that both his suit and rig are in good shape.

"That's good. Whew."

Suddenly, he began to experience flashbacks.

"Huh?"

The first image to show to him is a gunfight between his team and a group of unknown soldiers in what appears to be a facility.

 _"Take cover! 3 o'clock!"_ A voice shouted.

 _"I see that!"_

 _"He's activating the portal!"_

The young man put his right hand in his head as he was trying to get a sense of what happened before coming to the city. Another image flashed before his eyes showing him grabbing hold of a hand from a young female colleague wearing a suit with a princess knight theme.

 _"Shido!"_

The shouting suddenly made him go back to reality.

"Tohka..."

A moment of hesitation passed before Shido continued with his journey.

 _"Okay, Shido, think of what happened: we raided a facility in Charon, tried to stop a portal generator and I ended up here in some early part of the century. That's weird."_ He began to recall.

Suddenly, a young girl wearing an orange-and-black Gothic Lolita dress approached him.

"Oh look, what do we have here?"

"Who are you?" Shido demanded. "What do you want?"

"I've heard what you have said after appearing on the rooftop all of a sudden." She explained. "You've mentioned of appearing in the past, in this case right now, so I though you came from the future."

"So, you knew about what happened?"

"Doubtful." She began to take a curious look at his suit before making a gentle touch. "By the way, your suit looks futuristic and nice."

"Uhh...thanks?"

"Would you like to know what time period you are right now?"

"Yes, please." Shido replied.

She took her breath before revealing her response.

"Exactly what happened in your own timeline in 21st century?" A question was raised instead.

"Wait, I thought-"

"Something tells me you are not from this timeline. Hehe, just tell me."

"Well...for one, the Russian Civil War and World War III happened thanks to three guys named Imran Zakhaev, Vladimir Makarov and a certain General Shepherd. Fast forward to the future and the next wars we fought are against the Settlement Defense Front. A few hours a-"

"Wait...Russian Civil War? World War III?" She questioned.

"You don't know?"

"No, we never experienced that."

"Never?" Shido was confused.

The girl shook her head in reply.

"No... Just the Spacequake Disaster more than three decades ago."

""Spacequake Disaster?!" Shido was shocked. "Then... I'm in another dimension!?"

 **(Raizen High School - 0804 hrs.)**

As the first bell approaches, the students were arriving at the grounds in a mostly calm fashion. Shido was walking with Tohka to their classroom.

"You think you would be able to pass this time?" Shido asked.

"I hope so." She replied nervously. "After all those blunders I did in the past week, I'm not sure how I'm gonna feel when I finished it."

"Relax, Origami will give you some quick reviews before it starts."

"Thanks Shido, but even though..." Tohka began to have a hard time picking some words.

All Shido did to assure her was to give a small gentle pat on her head. It is enough to calm her down.

"Don't worry." He said some encouraging words. "Just try your best."

The Spirit's joyless face was being changed with a smile as she began to have hopes of passing the social studies quiz.

When the two reached their room for Class 2-4, a familiar white-haired lady was waiting for the two.

"Good morning Shido, Tohka." She greeted.

"Oh, hey Origami." Shido responded. "You've got the pointers Tohka asked?"

"I have them right here. Tohka, I'm hoping that you can do it this time."

"I will." Tohka responded in an unusually willing manner. Despite her rivalry with Origami for Shido's affection, she decided to set it aside for the time being.

A few minutes after, the bell rang to signal the start of the school day. Their homeroom teacher, a young-looking lady, arrived with her papers.

"Stand." The class representative said. "Bow"

The class bowed before beginning to greet their homeroom teacher.

"Good morning, Tamae-sensei." The class said in unison.

"Oh, hello kids. I hope you are ready for what's ahead today. You can sit down now."

The students then sat on their chairs.

 **(0832 hrs.)**

"So let me get this straight: you were on a mission to recover data in the hopes that you can find your lost sister and an accident from a portal generator sent only you here?" The girl asked for confirmation after listening to Shido's account.

"Correct." Shido confirmed. "Don't know about my teammates, either."

"I hope they are alright if they are separated here." She began to stand up preparing for her departure. "Well then, I think you better get going. A few "people" would be looking for you if they were to find out about who you are under that suit and helmet of yours."

"What people?"

"Two words: DEM Industries."

She gracefully bowed before stepping back to the shadows.

"Wait, I don't know them and...who are you?!"

"Kurumi Tokisaki. Nice meeting you... Shido Itsuka."

She disappeared in front of Shido's eyes.

"Okaaayy then..." He responded anxiously.

Unbeknownst to him, an invisible airship was watching the two's every move for the entire duration. Inside the airship, the commander of the aircraft, a cute middle school girl with red hair and wearing a red officer-style uniform was looking at the the monitor the moment he went inside the dimension.

"Kurumi, what are you doing there with him?" She questioned the actions of the most dangerous Spirit.

"Commander, I think you might want to see this." A man in his later years wearing glasses raised his discovery.

"What is it, Mikimoto?"

"The patch on his left arm. Zooming in now."

When the picture of the patch is on screen, it showed to the crew the appearance. It has a skull in the middle of the patch on a black background and spade with two red-and-white scythes formed in a cross, all passing through the open jaw and eyes. Two simple lightning bolts also appeared on the same location. On top of the patch, it reads "SPECIAL COMBAT AIR RECON", followed by SATO split in between the skull, the Roman numeral 6 in the mouth, and the abbreviation S.C.A.R. at the bottom.

"Special Combat Air Recon?" She wondered. "What is that?"

"Whatever it is, we have to keep monitoring." Mikimoto suggested. "That appearance suggested he could be from the military."

"No way. At that rate, the AST could be dealing with something even just as dangerous as any Spirit." She began to suck her lollipop.

"Any suggestions on dealing with this subject?" A woman whose hair covered the majority of her face asked.

"We might as well pick him up to make sure it doesn't attract too much attention."

Another window then showed the deployment of the Anti Spirit Team as they are responding to his arrival, not knowing what they are going to actually encounter.

"Guess they are about to find him right now."

 **(0844 hrs.)**

Shido continued moving under cover to avoid anyone seeing him. As he monitored the area, a young girl with blue hair appeared in front of him.

"So you are the one who has suddenly appeared in our world?" She greeted with a serious tone.

"How did you know about it?" Shido asked.

"We were watching you the moment you appeared. Regardless, you have to follow me. You are in grave danger."

"Danger?"

The girl nodded.

"Come, we better go."

"Alright."

The two then began to leave elsewhere. The girl then wondered about Shido due to his voice.

"Say, you sounded like my big brother." She compared to his sibling.

"Where is he now?"

"Raizen High School. He's currently taking some exams today."

"I see."

"Just between you and me, I'm Mana Takamiya."

"Nice to meet you, Mana."

A few minutes after, the AST arrived to secure the sight.

"You got anything?" Captain Ryouko Kusakabe, the leader and the oldest in the team, asked.

"Negative, ma'am." A subordinate responded. "Whatever it is, it must be a Spirit who might have slipped under the radar."

"Ah, we better keep looking for more leads."

They continued to scan the environment for any evidence of their arrival.

 **(Fraxinus - 0901 hrs.)**

Inside the airship, Mana was taking Shido to the bridge for further interrogation. On the way there, a flashback showing his little sister giving him a pendant appeared suddenly.

 _"When you do your duty, take some time to remember me every so often. Okay, Onii-chan?"_

 _"Don't worry, Kotori."_ Shido said while getting the pendant. _"I won't forget any of us, I promise."_

 _"Hehe. When you'll return back, we'll throw you a welcome-back party at Hakone."_

 _"If only if I return home alive, that is."_

The two exchanged a hug one last time before Shido will leave for his job as a SCAR operative.

 _"Stay safe...darling brother."_

The flashback ended as Shido returned to where he is now. The blue-haired girl took note of his brief pause.

"Are you okay there? You must be thinking of something."

"It's just about my sister, the day I left the house." Shido answered.

"What happened to her?"

Shido was hesitant to explain her fate.

"She...she..." Mana began to hold his hand for encouragement.

"Don't worry about it. Just say it."

"Well...she disappeared one day."

"What?!" The girl was shocked.

"While I was responding to an invasion from an army called the Settlement Defense Front, I tried to contact her hoping she may be alright." He testified. "After they are defeated, I returned home quickly to see my family. The moment I arrived, they told me that they lost her while the crowds tried to run away from the massacare."

"That's horrible. I feel sorry for your loss."

"Until just recently that is." Shido raised his head. "When we raided a facility, I found out that they have taken her elsewhere and they have kidnapped her for some kind of experiment called 'Project Efreet.'"

"Project Efreet?"

"Not much information at the moment. But I made a resolve to find her at all costs."

"I'm glad you are holding on to hope." The girl responded happily. "Now, if we may."

When the two reached the bridge, Shido was awed by its design. A large screen was one of the features.

"Wow. It reminds me of those spaceships back at home."

A blonde-haired man wearing a white suit approached Shido.

"Good morning." He greeted. "You must be the man we've been watching you for a while."

"Yes, I am."

"I'm Kyouhei Kannazuki, pleasure to make your acquaintances."

"Thank you. I need to see someone in charge."

"Certainly." He began to walk to the elevated platform to inform the commander of Shido's presence. "Commander, he wants to see you."

"Fine, fine. I'll see him."

When she approached Shido, he was shocked by her appearance.

"Huh...Kotori?!"

"You know me?" She questioned.

Shido began to take off his helmet to reveal his face. His blue hair and brown eyes made Kotori instantly realize who he is.

"Sh-Shido...?!" Kotori uttered.

"I-I..." Everyone inside the bridge was shocked at the words before Shido realized that she wasn't her real sister. "No. You're not her."

"Shido, what's going on?"

"The sister I know...I was trying to find her. We were getting closer to rescuing her but an accident brought me to this dimension."

"Wait, accident?"

"Yes."

She made an about face while thinking of something.

"Hmmmm...unsurprisingly, this is not the only one that has happened before."

"What do you mean?"

"Three weeks before, we detected the same energy signature not far from Tenguu City, the place you are currently right now. We even saw a bunch of guys carrying a container and some equipment."

"It could be possible that they have brought her here." Shido suspected. "To hide from us."

"Besides, who are the people that kidnapped the other me in your dimension?"

Shido took a few deep breaths to help him reveal the detail with some courage.

"DEM Industries."

The answer shocked everyone again. The corporation that tried to gain extensive influence while trying to capture and gain power from Spirits has a counterpart in Shido's dimension.

"Damn them." Kotori expressed her anger.

"I know how you feel." Shido tried to calm her down. "We found out two years ago what they are doing and we are currently hunting down the remnants of the circle."

"Consider yourself lucky, Shido. Maybe your sister could be here in THIS dimension as well, but I'll have to give you some history lessons to get you up to speed about here."

"Okay."

Kotori took a few steps forward as she began to explain to Shido some history lessons.

"From what you have been told by that girl in that dress, she briefly told you about a few things that happened here before, right?" She asked.

"Correct." Shido began to answer. "She told me about the "Spacequake Disaster" that happened three decades before."

"Oh, that... She was not wrong. It did happened and 150 million people lost their lives that day in the Eurasian continent."

"No way! 150 million?!" He was surprised.

"All thanks to a certain being known as a 'Spirit.' But their history is more complicated than that. Once, they are human beings and for some reason, they are exclusive to girls... Like me."

"You're a Spirit yourself?"

"Correct. That girl in the black dress you just met earlier is the most dangerous so far, an S-class Spirit."

"Kurumi Tokisaki." Shido recalled her name.

"We are happy that she didn't do anything dangerous to you other than admiring your looks and providing some hints. She killed more than 10,000 people for crossing the line."

"Don't tell me she is a cold-blooded murderer!?"

"She usually targets would-be rapist and those cruel to animals but sometimes, she would help my brother. Moving on from that, a bond with an item called a Sephira Crystal is all it takes to transform into one. Luckily, we have someone to seal their powers to prevent further destruction. That means the other you."

"Like what Mana told me, she said that he is school right now."

"Him and I are part of an organization called Ratatoskr, established to save the Spirits without resorting to violence. Then there are people who wants them dead without even knowing their problems or to gain power from them. The ones Mana was trying to help you avoid are the SDF's Anti Spirit Team and possibly DEM as well."

"Great, as if they are not the ones with crazy ambitions..."

"In the meantime, Mana will show you a place for you to stay. We'll give you some clothes as well to blend in with the surroundings ."

"I appreciate it, little sister." He sighed.

"Come on, Shido." Mana said as she began to guide him to his temporary shelter. She then raised one more question. "By the way, that patch on your arm... What is the 'Special Combat Air Recon' all about?"

"Special forces branch, Mana." Shido answered. "Assigned not only on the ground, but outer space as well. That's why I'm wearing the suit and helmet."

"Oohh... No wonder."

"Bit hard to explain but I'll try to make things simple."

 **(Spirit Manor - 1814 hrs.)**

As Tohka and Shido arrived at the Ratatoskr-established housing for sealed Spirits, they are bringing along groceries for dinner. Tohka was cheerful after passing the test.

"Still in the mood, I see?" Shido calmly asked her.

"Yeah. After passing the quiz, I think I could calm myself down now." Tohka replied. "I better thank Origami later when she comes."

"She will. There are a few things she has to finish so I would expect her to come here a bit late for dinner."

"Okay."

When they approached the door, Shido rang the buzzer to inform any occupant inside the apartment. When the doors opened, it revealed a young girl with a bright blue hair in a sundress and a rabbit puppet on her left hand.

"Welcome back, guys." She greeted. "How's the test?"

"Tohka managed to pass her social studies." Shido replied. "That's good news."

"Oh really, Tohka? Did you?" The puppet spoke via ventriloquism.

"Yeah, I did." Tohka replied.

"Yahooo! I'm proud of you!"

"That's enough, Yoshinon." The girl requested. "I think we have to get inside now."

"Uhh...alright, Yoshino." The puppet relented.

They then entered the apartment.

"Listen, Mana has brought someone here today but he told us he won't reveal himself to you until you meet him."

"Oh-kay?" Shido responded.

"Who could it be?" Tohka asked.

"We told you he will not say anything until you meet him!" Yoshinon rebuked. "Geez."

"Alright, alright."

When they reached the living room, a man was sitting on the sofa. Noticing their arrival, he stood up to see them and finally reveal himself to Shido and Tohka. The two were surprised by his appearance as he heavily bears a resemblence to the former.

"No way... You're...me!" He reacted.

"Yep. I know, because your sisters told me about you." The older Shido nodded.

"Mana and Kotori, I get it." The younger Shido then began to asked his counterpart a question. "So hey, what are you doing here?"

"I'm here because I am looking for Kotori."

"She's in the airship doing her job as commander of Fraxinus."

"No... The other her. She was sent here after being kidnapped and your sister told me that an earlier surge in energy was detected weeks earlier."

"Speaking of which, are you from another dimension?" Tohka curiously asked.

"Yeah, we are. And decades into the future..."

These words surprised them. Then, Kotori and Mana arrived to see the soldier.

"You should calm yourself down, Shido. We need to help him in every way possible." Kotori told his brother.

"So you found out earlier and you never told us."

"Sorry if I have to hold on to it for a while, just because you have those tests going on at the time."

"That's okay."

"By the way, his weapons are stored in the basement. No one except him will handle it." Mana informed.

"What are they?" Yoshino asked.

"A pistol and from what he told me, a hybrid energy sniper rifle that can become an assault rifle with a small change."

"Great...Nia would go gaga over that thing." As if on cue, energetic shouting can be heard from below.

"Hey guys, I found something! Hope they are props!" The shouting has made the other Shido worried.

"Oh damn, I hope she didn't accidentally switched off the safeties!" He began to rush downstairs to try and stop a potential accident from happening.

"Shido!" His counterpart shouted before he and the others began to follow.

Downstairs, Shido was scanning the room only to see a lady with ash grey hair and turquoise eyes fixiated on his EBR-800 and his suit. He showed himself in an effort to stop her.

"Ma'am, whatever you do, drop it." He warned.

"Why not? They look cool." The lady responded.

"I know they look and sound cool but deep down, they are real. Like, one push from the trigger and you would likely kill someone with it."

The girl then replied with a smile.

"I'm just joking. I know what they are." She offered an explanation before handing the rifle back to Shido.

"How do you know that?"

"Spoilers. Not much to say for now until you actually see it."

The others ran downstairs only to see the situation quickly resolved.

"Nia, I hope you didn't touch anything on his stuff by accident." He scolded.

"I know, Boy. I just found out when I came here."

The other Shido took notice of the conversation before beginning to ask a question regarding the energetic girl.

"Shido, you know her?"

"Well, her name is Nia Honjou and she is a manga artist." The younger Shido explained. "She is a Spirit like most of the girls here, except for Mana."

"I see." He sighed before Nia offered a handshake.

"Nice to meet you. What is your name?"

"Shido Itsuka, Special Combat Air Recon of the United Nations Space Alliance." The soldier replied.

"Did you say, "Space Alliance?""

"Well in my dimension, Earth has reached a point where space travel is quick like the ones in Star Trek or Star Wars and we have started colonizing planets for resources."

"That sounds like I want to see that dimension for myself."

"Only when he is done rescuing the other me from the DEM in their dimension." Kotori explained. "When he is done with that, you can see the dimension for yourself."

"Okay, fine." Nia then began to head to the living room. "By the way, I'll be using the living room in a while. Lots of panels to finish for today."

"I see."

"You know, if we have the time, tell me more about your dimension. I might make a manga about a person serving for a similar organization in a similar setting."

"If only if I can read it. I don't have much time here to be honest."

"That's okay. Only you and your sister knows more about it than us here combined."

"Hehehe... You will find out."

Then, Kotori began to receive a transmission on her earpiece. She pressed the button to answer it.

"What is it?" Kotori asked.

"Commander, we have detected an unknown energy signature eight miles west of Tenguu City." Kyouhei reported.

"Alright, we'll take care of it."

She turned his attention to the older Shido.

"Shido, get your gear ready. Looks like we have our first leads to your sister."

"Right." He nodded before beginning to get his equipment.

"I'm coming with you, Shido." Mana offered her help.

"You're a little girl. You will not survive a gunfight for long."

"To tell the truth, I once worked for DEM but after all the horrible things they did to me and some of my colleagues were revealed, I decided to defect to Ratatoskr."

"She's telling the truth, Onii-chan." Kotori pleaded.

Shido was trying to refuse the offer but the words of her sister's counterpart made him relent.

"I hope you're right about this." He hoped.

"My blood brother is one of the things I care more than the others. Even you or your sister doesn't deserve to go through the harsh experiments I went through."

"I know."

After that, the other Shido began to wear his suit and did a routine check on his equipment. After that, the two went to the door before Origami appeared in front of them.

"I'm coming with you as well." She followed.

"You can fight?" Shido asked.

Origami nodded.

"Right. Let's get going." He turned his attention to the others who decided to stay behind. "We'll be back, I promise."

"Stay safe out there." Tohka encouraged.

He nodded before leaving for Fraxinus.

"By the way, what's your name?" Shido asked.

"Origami Tobiichi." The white-haired girl introduced herself. "And I'd take you must be Shido Itsuka?"

"Yes I am."

"Good."

 **(Earlier)**

 **(Unknown location - 0956 hrs.)**

Inside the facility, DEM grunts were busy setting up their equipment to conduct further experiment on a test subject. Then, one of them arrived to report to the leader, a British man in his 40s and wearing a formal suit, of a recent development.

"Boss, looks like SCAR has been following us." He said before handing the tab over to him.

"Well, well, looks like they did?" He shrugged off the threat.

"What should we do, sir?"

He walked a few steps forward while thinking of a solution.

"No need to worry. Even if they do find us, we have our little trump card to play." He turned his attention to the girl with red hair. "Itsuka will be surprised to see his sister once again with some "enhancements.""

"I hope you are not treating the threat lightly."

The leader got hold of his EMC energy pistol and threatened the grunt with death.

"For once, try to stay calm and just trust me." He suggested and the grunt relented. "You are about to become a thorn on my side."

"Yes, sir."

"Thank you, lad. Now we must continue."

They then continued with their experiments.


End file.
